High-temperature-heating method



1920 2 Sheets-Sheet 1 M rch 1 1927.

a c. FIELD HIGH TEMPERATURE HEATING METHOD Original Filed March 4.

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Original Filed March 4. 1920 2 Sheets-SheetB woo/MM 931 (mime/1 Z Patented Mar. 1, 1927.

UNITED STATES PATENT OFFICE.

' CROSBY FIELD, OF NEW YORK, N. Y., ASSIGNOR TO CHEMICAL MACHINERY CORPORA- 'IION, A. CORPORATION OF NEW YORK.

,HIGH-TEMPERATURE-HEATING METHOD.

Application filed March 4, 1920, Serial No. 363,129. Renewed February 1, 1927.

This invention specifically considered includes an improved method for controlling chemical reactions at high temperatures, and specifically considered contemplates the provision of means whereby certain organic or hydrocarbon materials which require a tem perature greater than the boiling point ofwater, may be sulphonated, nitrated, distilled, fused, or subjected to various other N chemical reactions. In all chemical reactions the control of the temperature at which the reaction occurs is necessary in order to insure a maximum yield and thebest quality of the product. Under comparatively low temperatures,

which may be readily obtained by means of hot water or steam, such control is well known in the art. When, however, high temperature control-is attempted, the results so far obtained have not been satisfactory. For instance. when saturated steam is used for heating at high temperatures, the boilers and apparatus required are heavy, complicated, and generally unsafe. When superheated steam is used, apparatus of very large size is necessary because of the poor heat transfer between superheated steam and the wall of a vessel. Even in such cases, temperature control is quite difiicult because of the rapid decrease in temperature of superheated steam for each heat unit transferred. When certain special oils are used, the apparatus must be quite extensive because of the comparatively low heat transfer with liquids and in such large apparatus it is quite difiicult to obtain uniform distribution of heat over the entire surface of transfer. In addition, there is the ever present disadvantage of the carbonization of the oil which results in the precipitation or throwing ofi' upon the transfer surface of tarry and other non-heat conducting materials. As these oils are readily combustible, their use is always accompanied by fire hazard. When hot gases created by combustion are used, their poorheat transfer coeflicient necessitates the use of large apparatus and the difficulty of temperature control over a large surface results in non-uniform heating and relatively high heating in certain spots with a consequent loss of yield and deterioration in quality.

' By the term chemical reaction in the present disclosure is meant the combination of chemicals well known in the art, and in addition thereto the disassociation of chemicals by means of heat and theconcentration of chemicals in their various solutions, and

further, the change of chemicals from one state or atomic structure to another, as by dlstillatlon, subllmation, evaporation, concentration, precipitation, etc., and those other operations in industrial chemical processes by which chemical substances are transformed and obtained in the condition requisite to their subsequent use in the fine arts.

Although this delicate control of temperatureis necessary in all chemical reactions, it is especially desirable and necessary in reactions dealing with organic materials, and 111 partlcular dye stufi's, and intermediates which have been derived from coal tar and in connection with which my present invention has been used with pronounced success.

It is, therefore, an important object of my present invention to provide a method which is particularly designed for use in the promotion of various chemical reactions and preferably includes constantly maintaining mercury under a vacuum to practically eliminate pressure and thereby prevent noxious and poisonous fumes from injuriously affecting the operatives. 'In the use .of mercury as a heat transfer medium, I contemplate using only the vapor of the mercury for the transfer of heat. I am entirely familiar with the fact that mercury has heretofore been used for certain heating purposes, but in so far as I am aware, the use of mercur vapor in this particular field to which have above referred and in the manner to be hereinafter set forth, is entirely new. I also propose to superheat the mercury vapor, if necessary, to obtain higher tem eratures than a partial vacuum will pro uce. In some instances this superheated mercury vapor may be introduced directly into the. substance. being treated.

The invention therefore comprehends an improved method whereby very delicate temperature control at low pressure may be obtained with a correspondingly large transfer of heat per surface unit. As a result of my improved method of temperature control, the required apparatus is relativelysimple, may be readily installed, occupies a minimum of space and requires the attention of the 0 rative only at infrequent intervals.

I have employed the improved method with marked success in sulphonation and distillation processes as heretofore used inthe art in the production of beta naphthol, alpha naphthol, paranitraniline, antlu'acene, anthraquinone, acetanilid, naphthalene, phenanthrene, and believe that my invention is applicable tothe entire family of organic materials, of which there are several thousand compounds known in the art.

In the userof mercury and its vapor as a heat transfer medium for these organic compounds, two methods of utilization are apparent, one, where the mercury itself does not come into actual contact with the substance being treated, but transfers its heat through another medium, such, for example as steel. This method may be successfully employed in the sulphonation of naphthalene in the production of beta disulphonic acid. The other method consists in introducing the mercury vapor directly into the substance being treated, as for instance in the purification of anthracene and anthraquinone by mercury vapor distillation or sublimation in a manner similar to that in common use when superheated steam is emploIyled as the heat transfer agent.

e advantages of the use of mercury or mercury vapor for these chemical reactions may be briefly stated as follows. Mercury at atmos heric pressure has a boiling point of 357 -Hence, by maintaining the ap- Earatus in which mercury is used as the eat transfer medium'under partial vacuum, a comparatively hi h temperature can be obtained with practically no pressure, such slight ressure as may exist being from the atmosp here to the interior of the boiler or conduit containing the mercury vapor which is'niore or less desirable, since it will prevent the leakage of poisonous mercury fumes. Mercury is insoluble in either hot or cold water and also in hydrochloric acid, although it is soluble in nitric and concentrated sulphuric acids. Furthermore it has a freezing point below 39 C., and consequently will always remain liquid under normal operating conditions. In. addition, mercury has a molecular weight of 200.; hence it is very dense and because of such density, it is a comparatively easy matter to segregate the mercury from organic materials by gravitation. Furthermore, mercury readily forms amalgams with metals which are easily obtainable. Therefore, by inserting in parts of the apparatus where pressure might be created, metal with which the mercury will amalgamate, there will be no danger of the mercury fumes escaping to the atmosphere and dangerously affecting persons in the vicinity. Mercury will not form an amalgam with iron or steel,

nor does it wet the surface of these metals. Consequently, when it is used for the practice of my improved method which I shall now describe, a very large heat transfer per surface unit will be noted.

Having above stated the several salient features of my invention, the manner in which the improved method may be successfully carried out in practice will be fully understood from reference to the accompanying drawings in which I have illustrated two forms of apparatus which have been successfully employed .in'obtaining certain chemical reactions of organic materials and es ecially dye stuffs and intermediates thereo However, it will be understood that the illustrated examples of apparatus are merely suggestive and that my improved method of temperature and pressure control may be successfully practiced by means of or in connection with other apparatus than that herein specifically referred to.

In these drawings wherein similar reference characters designate parts throughout the several views, Fig. 1 is a diagrammatic sectional view showing one form of apparatus in which the transfer of heat" from the vaporized mercury is effected entirely by conduction and convection through .the wall of the vessel or container.

Fig. 2 is a similar view of another form of apparatus particularly designed for use in connection with chemical reactions involving the introduction of mercury vapor directly into the substance being treated.

Fig. 3 is a transverse section through the mercury boiler taken on the line 3-3 of Fig. 1.

Fig. 4 is a similar View showing a slightly modified form of the boiler.

Referring in detail to the drawings, and more particularly to Fig. 1 thereof, 1 designates a closed kettle orvessel having a chamber 2 to receive the substance to be treated and provided with a jacket 3 for the wall of said chamber. A rotarya' itator 4 is fixed upon the lower end of a s aft 5 extending into the chamber 2 and is driven through the medium of the gears 6 and the belt pulley 6, from any suitable convenient source of power. The mercury is heated and vaporized in a boiler 7 arranged within a suitably constructed furnace 8. 9 indicates the source of heat which may be obtained from gas, oil, coal or other combustible fuel. The

gases pass over a baflle wall 10-and between of the mercury will flow into said tubes and corresponding around the rods. These rods may extend above the level 13 of the mercury in the boiler 7 and be fixed to the top wall of the boiler as seen in Fig. 3, or the comparatively short rods 12 may be used and wholly submerged within the mercury. It will be understood that the mercury is heated to the boiling point and converted into vapor, such vopor collecting in the boiler above the mercury level 13 and passing therefrom through the pipe 14 into the jacket 3 of the vessel or container. Here the heat of the mercury vapor is given up and transferred through the wall of the vessel 1 to the substance contained therein and thereby effects the desired chemical reaction. Of course as the vapor gives up its heat it is partially condensed and falls into the lower end of the jacket 3 and finds an outlet through the connection 15 with the catchall 16 which is connected by a pipe or conduit 16 to the boiler 7. Such vapor as is not condensed in the jacket 3 passes into the condenser 17 which is connected to the upper end of the jacket. This condenser is in the form of a pipe coil and on the exteriorsurface of the coil water is delivered from a perforated pipe 19 connected to the end of the water supply pipe 18. The water from the ipe coil is collected in a pan or trough 20 rom which it flows through the drain 21. The lower end of the condenser 17 is connected to the catchall 16, so that the condensed mercury is returned with the condensation from'the jacket 3 to the boiler.

A vacuum is maintained upon the entire system and to this end a pipe 22 is connected to the catchall 16 and at its upper end has a return bend or leg 23 which is connected to. the vacuum pump 24. This vacuum pump is preferably of the hydraulic centrifugal type using mercury instead of water. This pump is driven by a motor 25 receiving current from the controller 27 through a lead 26.

In practice, the leg 23 of the pipe 22 should be at least 30 inches long so that the mercury which fills it can never be pulled.

back through the pipe 22 when the pump is Shut down. The speed of the pump, regulated by means of the controller 27, determines the degree of vacuum in the pipe 23, and in the catchall 16 and consequently in the jacket 3 and the boiler 7. The faster the pump is operated thegreater will he the quantity of liquid mercury which is drawn down the leg 23. This mercury is forced up into the pipe 28 connected to the pump. There is some mercury vapor which is not completely condensed in the condenser 17 and this vapor is drawn into pipe 22 and 23 where it then condenses and raises the level of the mercury in the leg 23. To give more complete control, I provide a by-pass 36 be tween the pipe leg 23 and the pipe 28 which is provided with a valve 37. By adjusting this valve some of the mercury may be recirculated and in this manner the degree of vacuum on the system may be more precisely controlled.

The pump 24 eventually forces all of the liquid mercury in the pipe leg 23 including the condensed vapor up into pipe 28. An

overflow pipe 32 is connected to the pipe 28' and has its lower end connected to the catchall 16. A normally closed valve 33 in the pipe 32 prevents the flow of the mercury from said pipe into the catchall. Hence the liquid mercury may continue to collect in pipes 32 and 28 until they are entirely filled, the pipe 28 beingopen to the atmosphere at its upper end. In the pipe 28 a float 29 is arranged and a pointer 30 is c'0n nected to the upper end of said float. This pointer moves on a scale 31 and indicates the filling of the pipe 28. Through the medium of this indicator, at the proper time, the valve 33 may be opened so as to permit the mercury to drain into the catchall 16 until the pointer 30fal1s to zero which may be suitably marked on the scale'31.

The pipes 23 and 28 are so proportioned that the volume of liquid mercury in the of air into. the system. At any desired point a vacuum gauge 35 may be connected by means of a pipe 34 in the system. 1

From the foregoing, the operation of the apparatus for carrying out my improved method will be readily understood. By the maintenance of a high degree of vacuum throughout the system, it will be apparent that the heat of the mercury vapor in the jacket 3 will be absorbed by the wall of the vesselil at substantially the initial vaporization tem erature of the mercury in the boiler 7. )wing to the absence of pressure, there will be no-appreciable decrease in the temperature of the vapor during its passage through the pipe connection 14 and the substance contained in the vessel .1 will therefore be quickly heated to the requisite degree in order to cause the desired chemical reaction. The return of the condensed mercury vapor to the boiler from the catchall 16 maintains a substantially uniform level of the mercury at all times in the catchall and the boiler and as rapidly as the liquidthirty inches and thereby prevent the ingress necessary apparatus is also very simple in 1ts construction as well as. compact in arrangement, so that it may be very readily installed in comparatively small space.

tion as that above referred to. However, in

' rial such as chamois.

this case the supply of saturated mercury vapor to the jacket. of the vessel 1 is controlledby means of a valve 38. The material is heated by the condensed vapor in this jacket, the mercury returning to the boiler through the catchall 16. The temperature in the jacket of the container or I vessel is controlled by the maintenance of a vacuum through the condenser 39 which is cooled by water entering at 40 and leaving at 41. The condensed mercury is returned by means of the pipe 42 through the catchall 16 to the mercury boiler. Non-condensed gases are removed by pump 43 Which d1scharges into trap 44. This trap s filled with copper or other metal with WhlCl'l mercury forms an amalgam, or a solution with WlllCll the mercury will react to form a compound.

A pipe coil 45 is arranged n the vessel or container 1, said pipe. coil be ng perforated. A superheater 46- is located 1n the mercury boiler furnace and is connected by pipe 47 to the coil 45. The assage ofthe mercury vapor from the boi er to the superheater 46 is controlled by a valve 48. In this manner it will be seen that highly superheated mercury vapor may be delivered through the perforated pipe coil 45 into the substance being treated and thereby carry off such substance by vapor distillatlon orvapor sublimation into a series of condensers 4?, 50 and 51. These condensers are respectively cooled by a cooling liquid entering at 52, 53, and 54, and leaving at 55, 56, and 57. In the condenser 49, those impurities which have a higher boiling point than mercury are condensed and are intermittently d1scharged into a vat 60 by the alternate opening andclosing of valves 61 and 62. The condenser 50 condenses the mercury together with the,material being distilled or subl med and these condensations fall into a trap 63 from which they are continually delivered into the vat 64. Because of the difference in density of the mercury and other materials,

the mercury will seek the lower level in the vat 64 and may be removed through astutable filter 65, preferably containing a mate- From the filter the condensed mercury is delivered into the catchall 16, such return of the mercury being controlled by a valve 66. The trap 63 is sufliciently deep so as not to interfere with the maintenance of the desired vacuum. The material which has thus been refined and floats on the surface of the mercury in the vat 64 may be removed from said vat through the door 67 The condenser 51 catches any material which may escape the previous condensers and its operation is similar to that of the condenser 49. The vacuum is maintained on the system by means of the pump 69 discharging into a trap 70 which contains a solution reacting with the mercury or a metal amalgamating therewith.

From the above it will be seen that in the operation of the apparatus last described an exceedingly delicate regulation of the temperature to which the substance being treated is heated, may be obtained. Thus the mercury vapor may be admitted to the jacket of the vessel or container for heating the material by conduction through the wall of the vessel and a superheated mercury vapor may also be delivered directly into the mass of material so that it will be quickly heated throughout to a uniform temperature. This latter operation is particularly employed in the purification of betanaphthol, anthracene, ant-hraquinone, and similar materials which necessitate the application of an exceedingly high temperaturevin order to effect the desired chemical reactions. However, I have also applied my improved method to the distillation, fusing, heating, etc., of certain inoiganic chemicals.

From the foregoing descriptiomthe construction of the several described forms of apparatus and their operation in carrying out my improved method will be clearly un derstood. In practice, I have found the several embodiments of apparatus herein dlsclosed to give very satisfactory results and to provi e very sim 1e and easily installed constructions whic do not require a very great amount of care and attention on the part of the operative. It is apparent, however, that the method as herein disclosed might also be successfully practiced by means of other alternative constructions ofthe apparatus, and it is accordingly to be under stood that inthis respect the invention is susce tible of many modifications and that I t erefore do not desire to be limited to the relative arrangement of the several features herein described except as defined in the appended claims.

I claim:

1. The herein described process which consists'in subjecting a body of mercury to heat for forming a vapor; applying the vapor in heat transferring relation to a body to be heated, thereby partially condensing the vapor; maintaining a substantial body of the thus condensed mercury in gravity flow relation to the body of mercury being subjected to heat but out of heat receiving relation therewith, thus returning such condensed mercury to the heated body of mercury; mercury vapor from the place of heat utilization and subsequently condensing the same and returning the latter condensate to the heated body of? mercury.

2. The herein described process which consists in maintaining a body of mercury under vacuum and subjecting it to heat for forming a vapor; applying the vapor in heat transferring relation to a body to be heated, thereby abstracting heat from a part withdrawing the remaining only of the vapor at the initial vaporization temperature and vacuum; continuously gumping another part of the mercury vapor om the region of such heat transference through a condensing region; returning the thus condensed mercury to the heated body of mercury; and subjecting the remnant uncondensed gases withdrawn by the pump ing, to the action of an amalgamating metal, to remove therefrom any remnant of mercury.

In testimony, that I claim the foregoing as my invention, I have signed my name.

CROSBY FIELD. 

